The petrographic and geochemical study of six (6) metabasites located in the Archean-Paleoproterozoic transition domain (SASCA domain, SouthWest Côte d'Ivoire) identified dolerites and gabbros. The thin sections revealed two textures: the doleritic texture (dolerite) and the granoblastic texture (gabbro). The dolerites are composed of plagioclase wands, pyroxene and olivine. Gabbros have a composition of pyroxene (clinopyroxene), green hornblende, plagioclase, biotite and rare quartz. Geochemical analysis, especially the major elements, corroborated the gabbroic character of the metabasites. Trace elements and rare earths helped to constrain the origin of the metabasites by showing: (i) their belonging to a tholeiitic series, (ii) a mantle source contaminated by the continental crust, and (iii) their emplacement in the field of intraplate or volcanic arc basalts.

The southern part of Toumodi-Fètêkro greenstone belt is located in the Center -Southeast of Ivory Coast. Petrographic study of volcanic and plutonic rocks shows three units. The first unit is composed of basaltic to rhyolitic lavas which imply effusive character. Then we have volcanosedimentary unit composed of pyroclastic formations (lapilli tuff, breccia, ash deposit and ignimbrites) and the pillow-lavas. Indeed, the presence of this last shows clearly that an explosive volcanism and a submarine effusive volcanism have occurred during during the setting of Toumodi-Fètêkro belt. Plutonic unit is constituted of gabbroic to granitic rocks. Sericite, chlorite, epidote observed in these rocks are consistent with the impacts of greenschist facies metamorphism. The rocks of the southern part of the Toumodi-Fètêkro greenstone belt are formed in a subduction context rather than in oceanic plateaus context because of the old inheritance, sometimes of Archean age, found somewhere in theBirimiandomain. The lithologies of the southern part of Toumodi-Fètêkro meet elsewhere in the other Birimian greenstone belts. Also, these lithologies are affected by a hydrothermal alteration due to the abundant veins of quartz, carbonates, sericite, chlorite, epidote, sulphides and oxides. However, volcanic show in some places amphibolit facies metamorphism. Keywords